Dapagliflozin attenuates LPS-induced myocardial injury by reducing ferroptosis.

Septic cardiomyopathy is a severe cardiovascular disease with a poor prognosis. Previous studies have reported the involvement of ferroptosis in the pathogenesis of septic cardiomyopathy. SGLT2 inhibitors such as dapagliflozin have been demonstrated to improve ischemia-reperfusion injury by alleviating ferroptosis in cardiomyocyte. However, the role of dapagliflozin in sepsis remains unclear. Therefore, our study aims to investigate the therapeutic effects of dapagliflozin on LPS-induced septic cardiomyopathy. Our results indicate that dapagliflozin improved cardiac function in septic cardiomyopathy experimental mice. Mechanistically, dapagliflozin works by inhibiting the translation of key proteins involved in ferroptosis, such as GPX4, FTH1, and SLC7A11. It also reduces the transcription of lipid peroxidation-related mRNAs, including PTGS2 and ACSL4, as well as iron metabolism genes TFRC and HMOX1.

Excessive accumulation of epicardial adipose tissue promotes microvascular obstruction formation after myocardial ischemia/reperfusion through modulating macrophages polarization.

BACKGROUND: Owing to its unique location and multifaceted metabolic functions, epicardial adipose tissue (EAT) is gradually emerging as a new metabolic target for coronary artery disease risk stratification. Microvascular obstruction (MVO) has been recognized as an independent risk factor for unfavorable prognosis in acute myocardial infarction patients. However, the concrete role of EAT in the pathogenesis of MVO formation in individuals with ST-segment elevation myocardial infarction (STEMI) remains unclear. The objective of the study is to evaluate the correlation between EAT accumulation and MVO formation measured by cardiac magnetic resonance (CMR) in STEMI patients and clarify the underlying mechanisms involved in this relationship. METHODS: Firstly, we utilized CMR technique to explore the association of EAT distribution and quantity with MVO formation in patients with STEMI. Then we utilized a mouse model with EAT depletion to explore how EAT affected MVO formation under the circumstances of myocardial ischemia/reperfusion (I/R) injury. We further investigated the immunomodulatory effect of EAT on macrophages through co-culture experiments. Finally, we searched for new therapeutic strategies targeting EAT to prevent MVO formation. RESULTS: The increase of left atrioventricular EAT mass index was independently associated with MVO formation. We also found that increased circulating levels of DPP4 and high DPP4 activity seemed to be associated with EAT increase. EAT accumulation acted as a pro-inflammatory mediator boosting the transition of macrophages towards inflammatory phenotype in myocardial I/R injury through secreting inflammatory EVs. Furthermore, our study declared the potential therapeutic effects of GLP-1 receptor agonist and GLP-1/GLP-2 receptor dual agonist for MVO prevention were at least partially ascribed to its impact on EAT modulation. CONCLUSIONS: Our work for the first time demonstrated that excessive accumulation of EAT promoted MVO formation by promoting the polarization state of cardiac macrophages towards an inflammatory phenotype. Furthermore, this study identified a very promising therapeutic strategy, GLP-1/GLP-2 receptor dual agonist, targeting EAT for MVO prevention following myocardial I/R injury.

Intravenously delivered mesenchymal stem cells prevent microvascular obstruction formation after myocardial ischemia/reperfusion injury.

Microvascular obstruction (MVO) after primary percutaneous coronary intervention (pPCI) is identified as an independent risk factor for poor prognosis in patients with acute myocardial infarction (AMI). The inflammatory response induced by ischemia and reperfusion (I/R) injury is considered one of the main mechanisms of MVO. Mesenchymal stem cells (MSCs) are a unique stromal cell type that confers an immunomodulatory effect in cardiac disease. The present study aimed to investigate whether immediate intravenous delivery of MSCs could be used as a potential therapeutic method to attenuate MVO formation. A cardiac catheterization-induced porcine model of myocardial I/R injury was established, and allograft MSCs were immediately delivered intravenously. Cardiac magnetic resonance (CMR) imaging was performed on days 2 and 7 after the operation to determine the infarct area, MVO, and cardiac function. The pigs with allograft MSCs showed decreased MVO and infarct size, as well as an improved left ventricular ejection fraction (LVEF). Histological analysis revealed decreased myocyte area, fibrosis, and inflammatory cell infiltration in the peri-infarct zone of pigs with allograft MSCs. Moreover, the concentrations of interleukin-1ß (IL-1ß), interleukin-6 (IL-6) and C-reactive protein (CRP) in the serum were reduced in the allograft MSC group compared to the control group. Flow cytometry indicated decreased natural killer (NK) cells in the peripheral blood and ischemic heart tissue in the pigs with allograft MSCs. In summary, allograft MSCs delivered intravenously and immediately after myocardial I/R injury can attenuate MVO formation in a porcine model through a decline in the number of NK cells in the myocardium.

Long non-coding RNA MEG3 knockdown attenuates endoplasmic reticulum stress-mediated apoptosis by targeting p53 following myocardial infarction.

Mounting evidence has indicated that long non-coding RNA maternally expressed gene 3 (lncRNA MEG3) regulates cell apoptosis, and is involved in a variety of diseases. However, its exact role in myocardial infarction (MI) has not been fully elucidated. In the present study, we firstly observed that the expression levels of the lncRNA MEG3 in infarct hearts and hypoxic neonatal mice ventricular myocytes (NMVMs) were up-regulated by quantitative real-time PCR (qRT-PCR). Then, we knocked down lncRNA MEG3 by lentiviral delivery in the myocardial border region following multipoint injection. Following 28 days of MI, the lncRNA MEG3 knockdown mice indicated better cardiac function, and less cardiac remodelling by ultrasonic cardiogram and histological analysis. In addition, we indicated that lncRNA MEG3 knockdown reduced myocyte apoptosis and reactive oxygen species production in MI mice model and hypoxic NMVMs. Furthermore, we revealed that knockdown of lncRNA MEG3 protected against endoplasmic reticulum stress (ERS)-mediated myocardial apoptosis including the induction of PERK-eIF2α and caspase 12 pathways. At last, we provided evidence that p53 was identified as a protein target of lncRNA MEG3 to regulate NF-κB- and ERS-associated apoptosis. Taken collectively, our findings demonstrated that lncRNA MEG3 knockdown exerted cardioprotection by reducing ERS-mediated apoptosis through targeting p53 post-MI.

Involvement of Apelin/APJ Axis in Thrombogenesis in Valve Heart Disease Patients with Atrial Fibrillation.

The mechanism underlying thrombosis in atrial fibrillation (AF) is not yet clearly understood. The apelin/APJ axis parallel and counter-regulate with the angiotensin system. The present study hypothesizes that apelin/APJ axis exert its anti-thrombus effect in normal left atrial tissue and is disrupted by up-regulated renin-angiotensin-aldosterone system (RAAS) signaling during AF. The specimens of left atrial appendages collected from patients with rheumatic mitral stenosis who underwent valve replacement were divided into 3 groups: sinus rhythm, AF+/thrombus-, and AF+/thrombus+. The amounts of angiotensin II receptor subtype 1 (AT1), apelin/APJ and its downstream plasminogen activator inhibitor-1 (PAI-1) were detected by western blot. The expression of apelin/APJ was significantly decreased in the AF+/thrombus+ group compared with the sinus rhythm and AF+/thrombus- groups. Meanwhile the expressions of AT1 and PAI-1 were highest in the AF+/thrombus+ group compared to the other two groups. Taken together, the present study reveals apelin/APJ axis might be correlated with thrombosis in patients with AF mediated by PAI-1.

Exposure to particulate matter induces cardiomyocytes apoptosis after myocardial infarction through NFκB activation.

Clinical evidence has indicated an increased myocardial infarction (MI) morbidity and mortality after exposure to air pollution (particulate matter<2.5 µm, PM2.5). However, the mechanisms by which PM2.5 aggravates MI remain unknown. Present study was to explore the adverse effect of PM2.5 on myocardium after MI and the potential mechanisms. Male mice with MI surgery were treated with PM2.5 by intranasal instillation. Neonatal mice ventricular myocytes (NMVMs) subjected to hypoxia were also incubated with PM2.5 to determine the role of PM2.5 in vitro. Exposure to PM2.5 significantly impaired the cardiac function and increased the infarct size in MI mice. TUNEL assay, flow cytometry and western blotting of Caspase 3, Bax and BCl-2 indicated that PM2.5 exposure could cause cellular apoptosis in vivo and in vitro. Besides, PM2.5 activated NFκB pathway and increased gene expression of IL-1ß and IL-6 in NMVMs with hypoxia, which could be effectively reversed by SN-50-induced blockade of NFκB translocation to the nucleus. In summary, air pollution induces myocardium apoptosis and then impairs cardiac function and aggravates MI via NFκB activation.

Effect of histone modifications on hMLH1 alternative splicing in gastric cancer.

hMLH1 is one of the mismatch genes closely related to the occurrence of gastric cancer. Epigenetic regulation may play more important roles than gene mutations in DNA damage repair genes to drive carcinogenesis. In this article, we discuss the role of epigenetic changes, especially histone modifications in the regulation of hMLH1 alternative splicing. Our results showed that hMLH1 delEx10, delEx11, delEx10-11, delEx16 and delEx17 transcripts were ubiquitous in sporadic Chinese gastric cancer patients and gastric cancer cell lines. Lower level of H4K16ac and H3ac was detected in hMLH1 exon 10-11 region in gastric cancer cell lines when compared with human gastric mucosal epithelial cell line GES-1. A significant decrease of hMLH1 delEx11 and delEx10-11 was observed in gastric cancer cell lines after trichostatin A treatment. H3K36me3 and H3K4me2 levels were lower in hMLH1 exon 10-11 and exon 16-17 regions in gastric cancer lines when compared with GES-1. Aberrant transcripts such as hMLH1 delEx11 and delEx10-11 were significantly higher in gastric cancer cell lines after small interfering RNA-mediated knockdown of SETD2 (the specific methyltransferase of H3K36). The hMLH1 delEx10 and delEx10-11 transcripts were increased after interference of SRSF2. Taken together, our study demonstrates that lower level of histone acetylation and specific histone methylation such as H3K36me3 correlate with aberrant transcripts in hMLH1 exon 10-11 region. SRSF2 may be involved in these specific exons skipping as well.

[The epigenetic effect on pre-mRNA alternative splicing].

Alternative splicing is a crucial step of the gene expression process in eukaryotes. It is a major cause for protein diversity and plays critical roles in differentiation, development, and disease. The studies on the mechanism of alternative splicing have traditionally focused on RNA sequence elements and their related splicing factors, but recent groundbreaking studies have shown that epigenetic factors play a key role in alternative splicing regulation. DNA methylation, chromatin structure and histone modifications interact with each other and regulate the process of alternative pre-mRNA splicing, forming a large and complex regulatory network. These findings suggest that epigenetic regulation not only determines the initiation of gene expression but also influences the outcome of pre-mRNA splicing. This review mainly focuses on the recent research progress in epigenetic regulation of pre-mRNA alternative splicing, including the functions of DNA methylation, chromatin structure and histone modifications in pre-mRNA alternative splicing, and speculates on its far-reaching effects on the study of human disease.

MSC-Derived Exosomes Mitigate Myocardial Ischemia/Reperfusion Injury by Reducing Neutrophil Infiltration and the Formation of Neutrophil Extracellular Traps.

Introduction: Acute inflammatory storm is a major cause of myocardial ischemia/reperfusion (I/R) injury, with no effective treatment currently available. The excessive aggregation of neutrophils is correlated with an unfavorable prognosis in acute myocardial infarction (AMI) patients. Exosomes derived from mesenchymal stromal cells (MSC-Exo) have certain immunomodulatory potential and might be a therapeutic application. Therefore, we investigated the protective role of MSC-Exo in modulating neutrophil infiltration and formation of neutrophil extracellular traps (NETs) following myocardial I/R injury. Methods: Exosomes were isolated from the supernatant of MSCs using a gradient centrifugation method. We used flow cytometry, histochemistry, and immunofluorescence to detect the changes of neutrophils post-intravenous MSC-Exo injection. Additionally, cardiac magnetic resonance (CMR) and thioflavin S experiments were applied to detect microvascular obstruction (MVO). The NLR family pyrin domain containing 3 (NLRP3) inflammasome was examined for mechanism exploration. Primary neutrophils were extracted for in vitro experiment. Antibody of Ly6G was given to depleting the neutrophils in mice for verification the effect of MSC-Exo. Finally, we analyzed the MiRNA sequence of MSC-Exo and verified it in vitro. Results: MSC-Exo administration reduced neutrophil infiltration and NETs formation after myocardial I/R. MSC-Exo treatment also could attenuate the activation of NLRP3 inflammasome both in vivo and in vitro. At the same time, the infarction size and MVO following I/R injury were reduced by MSC-Exo. Moreover, systemic depletion of neutrophils partly negated the therapeutic effects of MSC-Exo. Up-regulation of miR-199 in neutrophils has been shown to decrease the expression of NETs formation after stimulation. Discussion: Our results demonstrated that MSC-Exo mitigated myocardial I/R injury in mice by modulating neutrophil infiltration and NETs formation. This study provides novel insights into the potential therapeutic application of MSC-Exo for myocardial ischemia/reperfusion injury.

Research on prediction model of converter temperature and carbon content based on spectral feature extraction.

The flame of converter mouth can well reflect the change of temperature and composition of molten steel in the furnace. The flame characteristics of converter mouth collected by device can well predict the smelting process of converter. Based on the flame spectrum data set of converter mouth, this paper uses the BEADS algorithm and rough set attribute reduction algorithm optimized by genetic algorithm to extract the features of 2048-dimensional wavelength data. Through the model, eight indexes that contribute greatly to temperature and carbon content are selected, which are f-507, f-520, f-839, f-1073, f-1371, f-1528, f-1727 and f-1826. The MIC coefficients of the eight indicators with temperature and carbon content are calculated, and the MIC coefficients of the variables is small, and the selected indicators are representative. There was a significant correlation between temperature and C content. In BP neural network of temperature prediction model, it is found that the prediction accuracy of the training set is 0.99, the prediction accuracy of the test set is 0.99, the prediction accuracy of the verification set is 0.99, and the prediction accuracy of the whole set is 0.99. Through statistics, it is found that the hit rate of the temperature model in the range of ± 5 K is 88.7%, and the hit rate in the range of ± 10 K is 98.4%. and the RMSE parameter analysis shows that the average prediction error is 3.85 K. In BP neural network of carbon content prediction model, it is found that the prediction accuracy of the training set is 0.99, the prediction accuracy of the test set is 0.99, the prediction accuracy of the verification set is 0.98, and the prediction accuracy of the whole set is 0.99. Through statistics, it is found that the hit rate of the carbon contents model in the range of ± 0.05% is 94.0%, and the hit rate in the range of ± 0.10% is 98.3%, and the RMSE parameter analysis shows that the average prediction error is 0.021%. Finally, the universality of the model is verified by MIV algorithm.

Heart-gut microbiota communication determines the severity of cardiac injury after myocardial ischaemia/reperfusion.

AIMS: Recent studies have suggested a key role of intestinal microbiota in pathological progress of multiple organs via immune modulation. However, the interactions between heart and gut microbiota remain to be fully elucidated. The aim of the study is to investigate the role of gut microbiota in the post-ischaemia/reperfusion (I/R) inflammatory microenvironment. METHODS AND RESULTS: Here, we conducted a case-control study to explore the association of gut bacteria translocation products with inflammation biomarkers and I/R injury severity in ST-elevation myocardial infarction patients. Then, we used a mouse model to determine the effects of myocardial I/R injury on gut microbiota dysbiosis and translocation. Blooming of Proteobacteria was identified as a hallmark of post-I/R dysbiosis, which was associated with gut bacteria translocation. Abrogation of gut bacteria translocation by antibiotic cocktail alleviated myocardial I/R injury via mitigating excessive inflammation and attenuating myeloid cells mobilization, indicating the bidirectional heart-gut-microbiome-immune axis in myocardial I/R injury. Glucagon-like peptide 2 (GLP-2), an endocrine peptide produced by intestinal L-cells, was used in the experimental myocardial I/R model. GLP-2 administration restored gut microbiota disorder and prevented bacteria translocation, eventually attenuated myocardial I/R injury through alleviating systemic inflammation. CONCLUSION: Our work identifies a bidirectional communication along the heart-gut-microbiome-immune axis in myocardial I/R injury and demonstrates gut bacteria translocation as a key regulator in amplifying inflammatory injury. Furthermore, our study sheds new light on the application of GLP-2 as a promising therapy targeting gut bacteria translocation in myocardial I/R injury.

Transcriptome analysis of long non-coding RNAs of the nucleus accumbens in cocaine-conditioned mice.

Cocaine dependence involves in the brain's reward circuit as well as nucleus accumbens (NAc), a key region of the mesolimbic dopamine pathway. Many studies have documented altered expression of genes and identified transcription factor networks and epigenetic processes that are fundamental to cocaine addiction. However, all these investigations have focused on mRNA of encoding genes, which may not always reflect the involvement of long non-coding RNAs (lncRNAs), which has been implied in a broad range of biological processes and complex diseases including brain development and neuropathological process. To explore the potential involvement of lncRNAs in drug addiction, which is viewed as a form of aberrant neuroplasticity, we used a custom-designed microarray to examine the expression profiles of mRNAs and lncRNAs in brain NAc of cocaine-conditioned mice and identified 764 mRNAs, and 603 lncRNAs were differentially expressed. Candidate lncRNAs were identified for further genomic context characterization as sense-overlap, antisense-overlap, intergenic, bidirection, and ultra-conserved region encoding lncRNAs. We found that 410 candidate lncRNAs which have been reported to act in cis or trans to their targeted loci, providing 48 pair mRNA-lncRNAs. These results suggest that the modification of mRNAs expression by cocaine may be associated with the actions of lncRNAs. Taken together, our results show that cocaine can cause the genome-wide alterations of lncRNAs expressed in NAc, and some of these modified RNA transcripts may to play a role in cocaine-induced neural plasticity and addiction.

(1) H-nuclear magnetic resonance-based metabonomic analysis of brain in rhesus monkeys with morphine treatment and withdrawal intervention.

Comprehensive cerebral metabolites involved in morphine dependence have not been well explored. To gain a better understanding of morphine dependence and withdrawal therapy in a model highly related to humans, metabolic changes in brain hippocampus and prefrontal cortex (PFC) of rhesus monkeys were measured by (1) H-nuclear magnetic resonance spectroscopy, coupled with partial least squares and orthogonal signal correction analysis. The results showed that concentrations of myoinositol (M-Ins) and taurine were significantly reduced, whereas lactic acid was increased in hippocampus and PFC of morphine-dependent monkeys. Phosphocholine and creatine increased in PFC but decreased in hippocampus after chronic treatment of morphine. Moreover, N-acetyl aspartate (NAA), γ-aminobutyric acid, glutamate, glutathione, methionine, and homocysteic acid also changed in these brain regions. These results suggest that chronic morphine exposure causes profound disturbances of neurotransmitters, membrane, and energy metabolism in the brain. Notably, morphine-induced dysregulations in NAA, creatine, lactic acid, taurine, M-Ins, and phosphocholine were clearly reversed after intervention with methadone or clonidine. Our study highlights the potential of metabolic profiling to enhance our understanding of metabolite alteration and neurobiological actions associated with morphine addiction and withdrawal therapy in primates.

Taurine protects methamphetamine-induced developmental angiogenesis defect through antioxidant mechanism.

Investigations have characterized addictive drug-induced developmental cardiovascular malformation in human, non-human primate and rodent. However, the underlying mechanism of malformation caused by drugs during pregnancy is still largely unknown, and preventive and therapeutic measures have been lacking. Using 1H NMR spectroscopy, we profiled the metabolites from human embryo endothelial cells exposed to methamphetamine (METH) and quantified a total of 226 peaks. We identified 11 metabolites modified robustly and found that taurine markedly increased. We then validated the hypothesis that this dramatic increase in taurine could attribute to its effect in inhibiting METH-induced developmental angiogenesis defect. Taurine supplement showed a more significant potential than other metabolites in protecting against METH-induced injury in endothelial cells. Taurine strongly attenuated METH-induced inhibition of proliferation and migration in endothelial cells. Furthermore, death rate and vessel abnormality of zebrafish embryos treated with METH were greatly reversed by taurine. In addition, taurine supplement caused a rapid decrease in reactive oxygen species generation and strongly attenuated the excitable arise of antioxidase activities in the beginning of METH exposure prophase. Dysregulations of NF-κB, p-ERK as well as Bax, which reflect apoptosis, cell cycle arrest and oxidative stress in vascular endothelium, were blocked by taurine. Our results provide the first evidence that taurine prevents METH-caused developmental angiogenesis defect through antioxidant mechanism. Taurine could serve as a potential therapeutic or preventive intervention of developmental vascular malformation for the pregnant women with drug use.

High fiber diet attenuate the inflammation and adverse remodeling of myocardial infarction via modulation of gut microbiota and metabolites.

Introduction: High intake of dietary fiber is associated with lower incidence of cardiovascular diseases. Dietary fiber, functions as a prebiotic, has a significant impact on intestinal bacteria composition and diversity. The intestinal flora and metabolites generated by fermentation of dietary fiber not only affect the health of intestine but also play a role in many extra-intestinal diseases, such as obesity, diabetes and atherosclerosis. However, the role and the mechanism by which a high fiber diet contributes to the development of myocardial infarction is still unclear. Methods and results: Here we used an in vivo mouse model to investigate whether dietary fiber intake could protect against myocardial infarction. Our study demonstrated high fiber diet significantly improved cardiac function, reduced infarct size and prevented adverse remodeling following myocardial infarction. The protective effects of high fiber diet had a strong relation with its attenuation of inflammation. Moreover, we observed that high fiber diet could modulate the composition of intestinal flora and differentially impacted metabolites production, including the biosynthesis of bile acids and linoleic acid metabolism. Conclusion: Overall, the findings of this study provided mechanistic insights into the curative effect of dietary fiber on myocardial infarction with a specific emphasis on the potential role of microbiota-metabolism-immunity interactions.

Mobility speed predicts new-onset hypertension: a longitudinal study.

OBJECTIVE: The aim of this study was to investigate whether declining mobility and muscle strength predict new-onset hypertension in suburban-dwelling elderly individuals. METHODS: This study was designed as a longitudinal prospective cohort study. It was comprised of 362 individuals (mean age = 67.8 ± 6.2; 157 men) without hypertension at baseline. At baseline, all participants completed health questionnaires and underwent measurements of mobility [the Timed Up and Go test (TUGT) and 4-m walking test] and muscle strength (grip strength). At 1-year follow-up, we determined the number of participants who had developed new-onset hypertension. We then evaluated the relationship between above metrics and the development of hypertension. RESULTS: In the present study, 94 (26.0%) participants developed hypertension after 1 year. After adjusting for mixed factors, the TUGT scores [hazard ratio = 1.15; 95% confidence interval (CI), 1.10-1.31; P = 0.030] were positively associated with the development of hypertension, while the 4-m walking test scores (hazard ratio = 0.07; 95% CI, 0.01-0.47; P = 0.007) showed an inverse relationship with hypertension incidence. Grip strength (hazard ratio = 1.03; 95% CI, 0.99-1.06; P = 0.098) was not significantly associated with hypertension incidence. CONCLUSION: Our results indicate that people with declining mobility are significantly more likely to develop hypertension. Hence, improving mobility could be protective against hypertension for elderly individuals.

Bone marrow mesenchymal stem cell-derived exosomes attenuate cardiac hypertrophy and fibrosis in pressure overload induced remodeling.

The multiple therapeutic effects of bone marrow mesenchymal stem cells (BM-MSCs) have been verified in ischemic and reperfusion diseases. Exosomes are thought to play vital roles in MSCs-related cardioprotective effects. Recently, more and more evidences indicated that apoptosis and fibrosis were crucial pathological mechanisms in cardiac remodeling. Whether MSCs-derived exosomes could regulate cardiac hypertrophy and remodeling need to be explored. Murine BM-MSCs-derived exosomes were isolated by differential gradient centrifugation method. The transverse aortic constriction (TAC) mice model was established to promote cardiac remodeling. Cardiac function and remodeling were assessed via echocardiography and histology analysis. Myocytes apoptosis was determined by TUNEL fluorescence staining. Meanwhile, premature senescence was detected by ß-galactosidase (SA-ß-gal) staining. Related proteins and mRNA alternation were assessed via western blotting and quantitative reverse transcription polymerase chain reaction, respectively. MSCs-derived exosomes significantly protected myocardium against cardiac hypertrophy, attenuated myocardial apoptosis, and fibrosis and preserved heart function when pressure overload. In cultured myocytes, MSCs-derived exosomes also prevented cell hypertrophy stimulated with angiotensin II. One the other hand, exosomes promoted premature senescence of myofibroblasts vitro, indicating its anti-fibrosis effect in cardiac remodeling. Exosomes protected cardiomyocytes against pathological hypertrophy. It may provide a promising future treatment for heart failure.

Extracellular vesicles derived from Krüppel-Like Factor 2-overexpressing endothelial cells attenuate myocardial ischemia-reperfusion injury by preventing Ly6Chigh monocyte recruitment.

Background: The ischemia/reperfusion (I/R) process in patients with ST-segment elevation myocardial infarction (STEMI) triggers an immune response, resulting in myocyte death. Krüppel-Like Factor 2 (KLF2), which is highly expressed in endothelial cells (ECs) under laminar flow, exerts anti-inflammatory effects. In this study, we explored the role of small extracellular vesicles (EVs) from KLF2-overexpressing ECs (KLF2-EVs) in the immunomodulation and its implications in myocardial I/R injury. Methods and Results: The small EVs were isolated from KLF2-overexpressing ECs' supernatant using gradient centrifugation. Mice were subjected to 45 min of ischemia followed by reperfusion, and KLF2-EVs were administrated through intravenous injection. KLF2-EVs ameliorated I/R injury and alleviated inflammation level in the serum and heart. We employed the macrophage depletion model and splenectomy and showed that Ly6Chigh monocyte recruitment from bone marrow was the main target of KLF2-EVs. miRNA-sequencing of KLF2-EVs and bioinformatics analysis implicated miRNA-24-3p (miR-24-3p) as a potent candidate mediator of monocyte recruitment and CCR2 as a downstream target. miR-24-3p mimic inhibited the migration of Ly6Chigh monocytes, and miR-24-3p antagomir reversed the effect of KLF2-EVs in myocardial I/R. Conclusion: Our data demonstrated that KLF2-EVs attenuated myocardial I/R injury in mice via shuttling miR-24-3p that restrained the Ly6Chigh monocyte recruitment. Thus, KLF2-EVs could be a potential therapeutic agent for myocardial I/R injury.

Macrocyclic Peptide-Mediated Blockade of the CD47-SIRPα Interaction as a Potential Cancer Immunotherapy.

Medium-sized macrocyclic peptides are an alternative to small compounds and large biomolecules as a class of pharmaceutics. The CD47-SIRPα signaling axis functions as an innate immune checkpoint that inhibits phagocytosis in phagocytes and has been implicated as a promising target for cancer immunotherapy. The potential of macrocyclic peptides that target this signaling axis as immunotherapeutic agents has remained unknown, however. Here we have developed a macrocyclic peptide consisting of 15 amino acids that binds to the ectodomain of mouse SIRPα and efficiently blocks its interaction with CD47 in an allosteric manner. The peptide markedly promoted the phagocytosis of antibody-opsonized tumor cells by macrophages in vitro as well as enhanced the inhibitory effect of anti-CD20 or anti-gp75 antibodies on tumor formation or metastasis in vivo. Our results suggest that allosteric inhibition of the CD47-SIRPα interaction by macrocyclic peptides is a potential approach to cancer immunotherapy.

Mesenchymal stromal cell-derived exosomes attenuate myocardial ischaemia-reperfusion injury through miR-182-regulated macrophage polarization.

AIMS: Mesenchymal stromal cells (MSCs) gradually become attractive candidates for cardiac inflammation modulation, yet understanding of the mechanism remains elusive. Strikingly, recent studies indicated that exosomes secreted by MSCs might be a novel mechanism for the beneficial effect of MSCs transplantation after myocardial infarction. We therefore explored the role of MSC-derived exosomes (MSC-Exo) in the immunomodulation of macrophages after myocardial ischaemia/reperfusion (I/R) and its implications in cardiac injury repair. METHODS AND RESULTS: Exosomes were isolated from the supernatant of MSCs using gradient centrifugation method. Administration of MSC-Exo to mice through intramyocardial injection after myocardial I/R reduced infarct size and alleviated inflammation level in heart and serum. Systemic depletion of macrophages with clodronate liposomes abolished the curative effects of MSC-Exo. MSC-Exo modified the polarization of M1 macrophages to M2 macrophages both in vivo and in vitro. miRNA sequencing of MSC-Exo and bioinformatics analysis implicated miR-182 as a potent candidate mediator of macrophage polarization and toll-like receptor 4 (TLR4) as a downstream target. Diminishing miR-182 in MSC-Exo partially attenuated its modulation of macrophage polarization. Likewise, knock down of TLR4 also conferred cardioprotective efficacy and reduced inflammation level in a mouse model of myocardial I/R. CONCLUSION: Our data indicate that MSC-Exo attenuates myocardial I/R injury in mice via shuttling miR-182 that modifies the polarization status of macrophages. This study sheds new light on the application of MSC-Exo as a potential therapeutic tool for myocardial I/R injury.